Any Transport over MPLS (AToM): Remote Ethernet Port Shutdown

This Cisco IOS software feature allows a service provider edge router on the local end of an Ethernet over MPLS (EoMPLS) pseudowire to detect a remote link failure and cause the shutdown of the Ethernet port on the local customer edge router. Shutting down the Ethernet port on the local customer edge router prevents or mitigates a condition where that router would otherwise lose data by forwarding traffic continously to the remote failed link, especially if the link were configured as a static IP route.

Feature History for Any Transport over MPLS (AToM): Remote Ethernet Port Shutdown

Cisco IOS Release

Modification

12.0(30)S

This feature was introduced for Cisco 12000 Series Gigabit Ethernet line cards.

Finding Support Information for Platforms and Cisco IOS Software Images

Use Cisco Feature Navigator to find information about platform support and Cisco IOS software image support. Access Cisco Feature Navigator at http://www.cisco.com/go/fn. You must have an account on Cisco.com. If you do not have an account or have forgotten your username or password, click Cancel at the login dialog box and follow the instructions that appear.

•For Cisco IOS Release 12.0(30)S, this feature is implemented only for port mode Ethernet over MPLS (EoMPLS) connections between Cisco 12000 series Gigabit Ethernet line cards.

•The feature is asymmetric when only one provider edge router (PE) supports Any Transport over MPLS (AToM): Remote Ethernet Port Shutdown. A router that is not running the supported software of hardware could not detect the remote link failure.

Figure 1 illustrates a condition in an EoMPLS Wide Area Network, with a down Layer 2 tunnel link between a customer edge router (Customer Edge 1) and the service provider edge (Provider Edge 1). A customer edge router on the far side of the Layer 2 tunnel (Customer Edge 2), continues to forward traffic to Customer Edge 1 through the L2 tunnel.

Figure 1 Remote Link Outage in EoMPLS Wide Area Network

Previous to this feature, the Provider Edge 2 router could not detect a failed remote link. Traffic forwarded from Customer Edge 2 to Customer Edge 1 would be lost until routing or spanning tree protocols detected the down remote link. If the link was configured with static routing, the remote link outage would be even more difficult to detect.

With Any Transport over MPLS (AToM): Remote Ethernet Port Shutdown, the Provider Edge 2 router detects the remote link failure and causes a shutdown of the local Customer Edge 2 Ethernet port. When the remote L2 tunnel link is restored, the local interface is automatically restored as well. The possibility of data loss is thus diminished.

With reference to Figure 1, the Remote Ethernet Shutdown sequence is generally described as follows:

3. An RX_LOS error alarm is received by Customer Edge 2 causing Customer Edge 2 to bring down the interface.

4. Provider Edge 2 maintains its interface with Customer Edge 2 in an up state.

5. When the remote link and EoMPLS connection is restored, the Provider Edge 2 router enables the transmit laser.

6. The Customer Edge 2 router brings up its downed interface.

The Any Transport over MPLS (AToM): Remote Ethernet Port Shutdown feature is enabled by default for Ethernet over MPLS (EoMPLS), and can be disabled using no remote link failure notification command in the xconnect sub-mode. Use the show ip interface brief priveleged EXEC command to display the status of all remote L2 tunnel links. Use the show interface slot/number priveleged EXEC command to show the status of the L2 tunnel on a specific interface.

Note The no remote link failure notification command will not give notification to clients for remote attachment circuit status down.

There are no configuration tasks for the Any Transport over MPLS (AToM): Remote Ethernet Port Shutdown feature. The related show command output now reports operational status for all remote L2 Tunnels by interface.

All other trademarks mentioned in this document or Website are the property of their respective owners. The use of the word partner does not imply a partnership relationship between Cisco and any other company. (0804R)